OBJECTIVES: The objectives of this study are to assess PMNL function in HIV+ patients at different stages of disease over an extended period of time, determine if abnormal PMNL function predisposes patients to bacterial infections, and examine the various factors that may affect PMNL function. In addition, we will examine whether or not defects in PMNL function can be reversed by in vitro exposure to colony-stimulating factors. METHODS: Subjects. HIV-infected patients will be grouped according to CD4+ counts (> 500/mm3, 200-500/mm3, and < 200/mm3) and whether or not they are receiving anti-retroviral therapy. Controls groups will consist of patients at risk for HIV infection with a negative HIV antibody test and healthy volunteers without risk factor for HIV infection. Clinical data, including age, risk factors for HIV infection, staging (CDC, Walter Reed), and the occurrence of bacterial infections will be recorded. PMNL function. PMNLs will be isolated from patients and controls and a battery of function assays performed. Chemotaxis, adherence, aggregation, superoxide production in response to stimuli (f-met-leu-phe, PMA, and opsonized zymosan) in a superoxide dismutase (SOD) inhibitable cytochrome C reduction microassay, phagocytosis, and bacterial killing will be determined for patients and compared to the paired control. Effect of colony-stimulating factors on PMNL function. PMNLs will be preincubated with granulocyte and granulocyte-macrophage colony-stimulating factors (G-CSF, GM-CSF) and tested with the battery of assays described above. Factors associated with abnormal PMNL function. We plan to measure circulating levels of immunoglobulins, fibronectin, PMNL chemoattractants (C5a, leukotriene B4, and platelet activating factor), cytokines that affect PMNL function (TNF, IL-1, and gamma-interferon), and colony- stimulating factors, and correlate levels with PMNL function. Fluorocytometry will be used to detect anti-neutrophil antibodies and the expression of PMNL surface markers that are associated with normal PMNL function. Methods of Analysis. The results of PMNL function tests will be reported as the mean plus/minus standard deviation. The means of groups will be analyzed by the Student's test and ANOVA. The relationship between stage of disease and PMNL function will be analyzed by linear regression and ANOVA. Associations between bacterial infections and PMNL function, anti- retroviral therapy, circulating factors, anti-retroviral therapy, circulating factors, anti-PMNL antibodies, surface markers, and other parameters will be analyzed by multivariate analysis.